In a plant facility or the like, a liquid supplying facility may be provided, which rapidly supplies a liquid stored in a container in a large flow rate. For instance, as an example of such a liquid supplying facility, a liquid supplying facility for supplying a large amount of cooling liquid rapidly to a high-temperature portion may be provided for a power plant or the like. At this time, by detecting a liquid level change of the liquid stored in the container and calculating the flow rate of the supplied liquid from the liquid level change, it is possible to determine the supply state of the liquid (e.g. the supply state of the cooling liquid to the high-temperature portion inside the power plant).
As a typical technique for detecting the liquid level of a liquid stored in a liquid container, for instance, there is a technique of obtaining a differential pressure between a pressure of a pipe in communication with a gas-phase section inside the liquid container and a pressure of a pipe in communication with a liquid-phase section inside the liquid container, and calculating a liquid level on the basis of the differential pressure. As an example of the liquid level detection device for calculating a liquid level on the basis of the differential pressure, Patent Document 1 discloses the following liquid level detection device.
The liquid level detection device disclosed in Patent Document 1 is configured to prevent liquid level measurement errors due to a temperature difference formed inside a pipe, in a pipe configuration for measuring the liquid level inside a liquid tank. The liquid level detection device disclosed in Patent Document 1 detects the differential pressure between an upper liquid level detection pipe and a lower liquid level detection pipe each connected at an end to the gas-phase side and the liquid-phase side of a balance pipe to which the liquid level inside the liquid tank is introduced. The differential pressure is obtained from a difference between two pressure values measured by two diaphragm portions for pressure measurement disposed on each of the second ends of the upper liquid level detection pipe and the lower liquid level detection pipe.
Furthermore, in the liquid level detection device disclosed in Patent Document 1, water is stored in the second ends of the upper liquid level detection pipe and the lower liquid level detection pipe, to prevent high-temperature steam formed by evaporation of the liquid in the liquid tank into a gas phase from increasing the temperature of the diaphragm portion for pressure measurement disposed in the upper liquid level detection pipe which is in communication with the gas-phase side of the balance pipe. As a result, with the liquid level detection device disclosed in Patent Document 1, it is possible to prevent liquid level measurement errors due to a meat temperature difference between the measurement diaphragm portion at the side of the upper liquid level detection pipe and the measurement diaphragm portion at the side of the lower liquid level detection pipe.